Bio-wastes – what are they worth ? Eric Evans. Why the interest in bio-wastes ? Methanogenesis...

Bio-wastes – what are they worth ?

Eric Evans

Why the interest in bio-wastes ?

Methanogenesis

Landfill ban on Liquids

Landfill Tax£82.60

High Fertiliser

Costs

Fertilizers have many advantages

• Easy to store and handle• Convenient to apply• Concentrated form • Accurate analysis of

nutrients• Readily available nutrient

form

High dependence on energyin manufacturing process

leading to high cost.Long term availability

Bio-wastes - what can they offer ?

• Low cost materials

• Local supplies

• Additional source of organic matter Sulphur, Magnesium and Trace Elements

• High sustainability value

• Slow release of nutrients

However – there are drawbacks !

• Bulky materials• Relatively low nutrient concentrations• High handling and spreading costs• Narrow application window • May require specialist application equipment• Slow rate of nutrient release may be a

disadvantage

Their use is highly regulated by the

Environment Agency

What is available in our area ?

Digestate from Treated Sewage Sludge

PAS 100 Green Compost

Food WasteBlood

Water Cake

Non-PAS 100 Green

CompostAD Food Digestate

Paper Sludge

Eggshells

Segregated Green Waste Compost Large scale compost

production is relativelynew to the UK.

Previously green waste sent in landfill sites.

Currently there are over 150 sites operating in the UK processing nearly 3 million tonnes of green waste annually.

Quality Compost

This defines Compost as a product rather than a waste

Its use in agriculture does not require an exemption from the EA

There are 6 PAS 100 accredited Compost Producers in the North East

Land Spreading of Non-Hazardous Waste - Non PAS 100 Compost

Nutrient Value of Compost

Typical Analysis (Fresh weight basis)

Dry Matter 50 – 65%pH 7.5 – 8.5OM 50 – 60%Nitrogen 0.7 – 1.4%Phosphorus 0.2 – 0.4% P205

Potassium0.4 – 0.6 % K20Magnesium 0.2 – 0.3% Mg0Sulphur 0.1 – 0.25% S03

Calcium 1.3 – 2.0%

Recommendation

One tonne contains- 8.76 kg N 4.97 kg P205

6.9 kg K20 3.82 kg Mg0and 3.97 kg S03

20 t ha Dressing provides

175 kg N (18 kg RA) 99 kg P205 (50 kg RA)138 kg K20 (110 kg RA) 76 Kg Mg0 (38 kg RA) 79 kg S03 (40 kg RA)

Paper SludgePaper Sludge

Nutrient Value of Paper Sludge

Typical Analysis (Dry Matter Basis)

• Dry Matter 38 – 45%• pH 7.5 – 7.9• OM 25 – 30%• Nitrogen 0.2 – 0.4%• Phosphate 300 – 500 mg/kg• Potassium 120 – 200

mg/kg• Magnesium 0.2 – 0.3%• Sulphur 0.08 – 0.1%• Calcium 25- 30%

Recommendation

One tonne contains -1.7 kg N 0.9 kg P205

0.28 kg K20 and 1.94 kg Mg0

60t ha Dressing provides

102 kg N (5 kg RA)56 kg P205 (28 kg RA)17 kg K20 (13 kg RA)116 kg Mg0 (58 kg RA)

Water Cake

• Northumbrian Water have 9 Water Treatment Facilities throughout the Region

• Drinking water is extracted primarily from rivers and reservoirs

• Purification is achieved by flocculation of organic and inorganic particles by aluminium and iron compounds

Solid Sludge

Nutrient Value of Water Cake

Typical Analysis (DM Basis)

Dry Matter 40 – 60%pH 4.0 – 6.8OM 45 – 58%Nitrogen 0.6 – 0.9%Phosphorus 0.1 – 0.3% P205

Potassium 300 – 2000 mg/kgMagnesium 200 – 1800 mg/kgCalcium 0.1 – 0.5%

Recommendation Horsley Treatment WorksOne tonne contains- 2.1 kg N 0.44 kg P205

0.28 kg K20 and 0.11 kg Mg0

100 t ha Dressing provides

210 kg N (42 kg RA)44 kg P205 (22kg RA)28 kg K20 (22 kg RA)11 Kg Mg0 (5 kg RA)

AD Digestate

Agricultural Plants

Waste Plants

BiomassPre-

treatment

AnaerobicDigestion

Post-treatment Biofertiliser

Biogas

Electricity

CHP

Heat

The Anaerobic Digestion Process

Land Spreading of DigestateDefinition of WASTE

Traditionally manure and slurry are not considered waste when

spread directly on land as a fertiliser

Energy crops grown for AD are not considered waste

Digestate is no longer considered a waste if the only feedstock is manure,

slurry or energy crops

Off Farm Feedstocks are considered as WASTE

EA Deployment

PAS 110 Accreditation

Liquid Solid

MixtureD.M. 20 – 30%

D.M. 1 – 3%

D.M. 3 -14%

Nutritive Value of Digestate ( Food Waste)

Typical Analysis (Fresh Wt.)

Dry Matter 3 - 4%pH 8.2 – 8.5OM 2 – 3%Nitrogen 0.3 – 0.5%Phosphorus 300-600 mg/kgPotassium 1700–3000 mg/kgMagnesium 100–250 mg/kgSulphur 200-600 mg/kg

Recommendation

One m3 contains-

4.2 kg N 1.4 kg P205

3.65 kg K20, 0.25 kg Mg0, and

3.16 kg S03

50 m3 ha dressing provides

210 kg N (147 kg RA) 70 kg P205 (35 kg RA)183 kg K20 (128 kg RA) 13 Kg Mg0(7 kg RA)158 kg S03 (79 kg RA)

Nutritive Value of Digestate ( Sewage Sludge Derived)

Typical Analysis (Dry Matter basis.)

Dry Matter 25 - 30%pH 8.2 – 8.8OM 60-70 %Nitrogen 5 – 6 %%Phosphorus 3 - 5% P205

Potassium0.2 – 0.4% K20Magnesium 0.1 – 0.3 % Mg0Sulphur 1.0 –2.0 % S03

Recommendation

One m3 contains-

16.95 kg N 13.2 kg P205

0.49 kg K20, 0.5 kg Mg0, and

10.0 kg S03

14 m3 ha dressing provides

237 kg N ( 166 kg RA)185 kg P205 ( 93 kg RA) 7 kg K20 ( 5 kg RA) 7 Kg Mg0 ( 4 kg RA)140 kg S03 ( 70 kg RA)

To Recap

Waste Type

Form Rate OM pH N P K Mg S

Compost Solid 20 t ha √ >7 √ √√ √√ √ √Paper Sludge

Solid 60 t ha √√ > 7 √ × × √ ×

Water Cake Solid 100 t ha √√ < 7 M M M × √Food Digestate

Liquid 50 m3 M > 7 √ √√ √√ × √√

Sewage Digestate

Liquid 14 m3 × > 7 √√ × × × √√

What are their NPK values ?

Compost

Paper Sludge

Water Cake

Food Digestate

Sewage Digestate

£12.00 / t

£2.00 / t

£2.00 / t

£6.00 /t

£20.00 /t

How much do you value

Organic Matter ?

Sulphur

Mg and T.E.

Thank you for your attention